[ RadSafe ] Radon Travel in Granite

[dckosloff at firstenergycorp.com]

Hi Kai ( I like the sound of that, but I am probably pronouncing it wrong),
Al and all,

This seems to be related to any discussion of the radioactivity from
granite:
http://www.junkscience.com/apr01/crstudy.htm

"Radiation Sources at the U.S. Capitol and Library of Congress Buildings"

Unfortunately, I don't have any granite counter tops.  How about marble
window ledges?

Enjoy,
Don Kosloff, License Renewalist
6310 N. Harris Harbor Drive
Oak Harbor OH 43449




                                                                           
             "Kai Kaletsch"                                                
             <eic at shaw.ca>                                                 
             Sent by:                                                   To 
             radsafe-bounces at r         "al gerhart"                        
             adlab.nl                  <webmaster at solidsurfacealliance.org 
                                       >, <radsafe at radlab.nl>              
                                                                        cc 
             07/30/2008 09:51                                              
             PM                                                    Subject 
                                       Re: [ RadSafe ] Radon Travel in     
                                       Granite                             
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Hi Al and all,

Aside from any incremental increase in radon or gamma exposure (which I
don't tend to get too excited about), 0.25% U ore would NOT be my first
choice of food preparation surface. If those numbers are correct, then it
is
important that a sample of the same material be made available for testing
by the other stake holders in this (by now somewhat politicized) issue.

0.25% U is quite high and, at least in Canada, there are several
regulations
dealing with radioactive materials that kick in at much lower levels. For
example, 0.05% U (5 times lower than your rock) is considered 'source
material' and is a 'controlled nuclear substance' (even if it is contained
in a granite countertop) and a license is required to export the material
from Canada. So, if your slab of granite came from Canada, and the exporter

didn't approach our nuclear regulator to get a license ... You can see our
Nuclear Non-proliferation Import and Export Control Regulations here:
http://laws.justice.gc.ca/en/n-28.3/sor-2000-210/153934.html?noCookie

Before, you asked if there is a quick and dirty way of getting from cpm or
mR/Hr to ppm. You can get in the right ballpark if you take readings on a
bunch of  normal granite, average the readings, assume that corresponds to
Dan's value of ~ 10 ppm and scale the result of your sample.

You can also calculate a dose rate for a given geometry as a function of
uranium content. I have a program on my website that does this (see
http://members.shaw.ca/eic/Tools/JavaShield/Index.html , read the
documentation and use the rectangular source geometry). If you are using a
pancake probe, these are not energy compensated and your reading will be
off
by a bit. More importantly, make sure you put ~ 1 mm sheet of aluminum (or
similar) between the source and the pancake. Otherwise, your detector will
see alpha and beta radiation and your mR/Hr reading will be meaningless
(you
want to see gamma). That is probably how you got your 10.5 mR/Hr reading,
which is too high, even for 0.25%U.

Regards,
Kai

Kai Kaletsch
Environmental Instruments Canada Inc

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